In serial input/output communications, a single or multiple re-driver or re-timer device(s) are often used to extend the reach of the communication link. As serial bit data rates increase the signal integrity requirements lead to more complex buffering (re-driver and re-timer) devices, which in turn require increased levels of configuration.
One problem is that the configuration of the buffering devices often requires individual non-volatile memory (NVM) devices for each buffer. These NVM devices contain the configuration information for each of the re-timer or re-driver devices (which typically include default values) and in cases where there are multiple serially-connected devices they will have different configurations. This is an issue for Ethernet applications on large system boards.
Currently, end-point devices can only use predefined functions to configure intermediate devices as part of the Auto-Negotiation process. Configuration registrations can only be accessed by the MDI (Medium Dependent Interface) or similar out-of-band bus, which requires addition system complexity and components.